For centuries, cereal crops have supplied the means for sustaining life. Cereal crop production plays a crucial role in maintaining a viable economy in the predominantly agricultural regions of the world. Cereal crops include wheat, rice, barley, sorghum and the like. Grass weeds pose a particular problem in cereal crop production in that many herbicidal agents which control grass weeds also cause injury to the target crop species due to the similarity of the weed and crop monocotyledenous plant species. An especially difficult weed plant in cereal crop production is the Aegylops genus (goatgrasses) such as Aegylops cylindrica Host., Aegylops triuncialis L. Barb., Aegylops ovata L. and the like. This plant genus is physiologically and genetically similar to wheat and is difficult to control without concomitant injury to the wheat crop. The presence of goatgrass in wheat production can cause up to 30% yield reduction and contaminate the harvested crop, thus reducing its milling quality and potential use as seed for future crop production.
To date, the known methods to avoid or control the presence of goatgrass in cereal production is to plant alternative crops or allow the fields to lie fallow for some period of time. However, these methods are time-consuming, costly and not always practicable.
Imidazolinone herbicidal agents such as those described in U.S. Pat. No. 4,798,619 and U.S. Pat. No. 5,334,576 are known to be effective over a broad spectrum of broadleaf and grass weed species. These patents describe compounds having the structure: ##STR1## wherein A, B, R.sub.1, R.sub.2, W, X, Y and Z represent a wide variety of substituents. Said patents further describe the preemergence and postemergence herbicidal activity of more than a thousand of such pyridine and quinoline imidazolinones. U.S. Pat. No. 5,334,576 specifically discloses the compound 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-(methoxymethyl)nicotini c acid and the herbicidal activity thereof against a wide variety of broadleaf and grass weed species. However, U.S. Pat. No. 4,798,619 and U.S. Pat. No. 5,334,576 do not disclose that 2-(2-imidazolin-2-yl)pyridines and quinolines are active against Aegylops weed species either alone or in the presence of a cereal crop.